CVE-2025-30258Public exploit

Signature-verification denial via malicious subkey shadowing

Published Mar 19, 2025 · Updated Mar 19, 2025

Improper certificate validation in GnuPG before 2.5.5 allows attackers to disrupt signature verification through a crafted import. During key selection, gpg accepts malicious subkeys with reused fingerprints without rejecting invalid usage flags or missing cross-certification, causing them to shadow legitimate primary signing keys. A user must import the crafted certificate; affected keyrings then select the broken subkeys and cannot verify signatures from the matching legitimate keys.

CVSS severity2.7
Low
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper certificate validation in GnuPG before 2.5.5 allows attackers to disrupt signature verification through a crafted import. During key selection, gpg accepts malicious subkeys with reused fingerprints without rejecting invalid usage flags or missing cross-certification, causing them to shadow legitimate primary signing keys. A user must import the crafted certificate; affected keyrings then select the broken subkeys and cannot verify signatures from the matching legitimate keys.

The record

CVE
CVE-2025-30258
Published
Mar 19, 2025
Updated
Mar 19, 2025
Vendor
The GnuPG Project
Product
GnuPG
Classifications
CWE-754, T1687
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 19, 2025CVE publishedPublication date reported by the CVE source.
  2. Mar 19, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <2.5.5

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

The GnuPG Project · GnuPGversion=0 <2.5.5

Published CVSS scores

2.7MITRECVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:C/C:N/I:N/A:L
4.7NIST NVDCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-754Improper Check for Unusual or Exceptional Conditions
T1687Exploitation for Defense Impairment

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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